Dr. Ph. Martin's Radiant Concentrated Water Color is produced in an extremely concentrated form to achieve the greatest possible brilliance. Each liquid color comes in an iconic 0. 5 oz (15 ml) glass bottle package with its own eyedropper. Dr. Ph. Martin's colors are primarily formulated for use in graphic arts work on paper surfaces intended for reproduction (e. g. cartooning, illustration, and other graphic arts), and are especially popular for airbrushing. Like all aniline dye base colors, they are fugitive when exposed to direct sunlight over time. For lightfast, archival watercolor use Dr. Ph. Martin's Hydrus Fine Art Watercolor. 56 colors are available.